Effects of WO3 on the microstructure and optical transmittance of PLZT ferroelectric ceramics

The influence of the WO3 addition as sintering aids on the structural, microstructural and optical properties of (Pb,La)(Zr,Ti)O3—PLZT based ceramics was investigated. Ferroelectric (Pb0.9La0.1)(Zr0.65Ti0.35)0.975O3 + x wt% WO3 (x = 0.0, 0.5, 1.5 and 2.0) ceramics were densified by oxygen assisted uniaxial hot pressing. From the XRD results it was found that the hot pressed samples displayed single pseudocubic perovskite phase. EDS analysis evidenced the presence of WO3 rich phase at the grain boundaries. An inhibition of grain growth and an evolution from transgranular to intergranular fracture behavior was observed, as a consequence of the formation of a PbO–WO3 liquid phase, as the amount of WO3 addition was increased. The optical transmittance in the visible and infrared range was decreased due to the presence of the liquid phase in grain boundaries, for WO3 content lower than 2.0 wt%.